Scalable nanoconfinement-enhanced electro-Fenton process for wastewater purification via boosting singlet-oxygen generation.

Nanoconfined catalysts have been widely employed to promote singlet oxygen (1O2) generation, thereby improving the removal of contaminants from real wastewater. However, constructing nanoconfined microenvironments typically requires sophisticated architecture and complex nano-engineering. Here, instead of elaborate nanoscale designs, we leverage the intrinsic three-dimensional scaffold of carbon felt together with PTFE encapsulation to immobilize oxygen-doped carbon nanotube-supported FeNi layered double hydroxide (FeNi-LDH/OCNT) within the felt matrix, constructing a novel, electrode-scale integrated nanoconfined cathode (LDH/OCNT-CF). The LDH/OCNT-CF cathode completely removed ofloxacin (OFL) within 50 min, exhibiting an apparent rate constant of 0.083 min-1, and 63.6% TOC removal efficiency was attained after 180 min. Moreover, the system achieved COD and TOC removal efficiencies of 64.6% and 49.3% for medical wastewater, respectively. The corresponding energy consumption was 18.2 kWh (kg COD)-1, which is notably lower than those reported for most comparable EF systems treating actual wastewater. Density functional theory (DFT) calculations reveal that spatially confined FeNi-LDH/OCNT favors cooperative attack by 1O2 and ·OH on the electron-rich sites of OFL, facilitating OFL mineralization. Overall, this work circumvents the elaborate nanoscale catalyst design by implementing nanoconfinement at the electrode level, and the resulting integrated cathode is readily scalable, highlighting its practicality for real-world water treatment.